A recent study by Farallon Institute scientists examined the collapse of the anchovy population in California, which appeared to be unrelated to fishery effects. We developed new estimates of abundance of northern anchovy (Engraulis mordax) from egg and larval densities for the period 1951-2011 in the Southern California Bight. Previous estimates utilizing mean density over the area have a bias because of the nearshore concentration of CalCOFI sampling stations and the anchovy population tendency to contract into that area when abundances are low. We developed total egg and larval population estimates for January and April, formed a combined ichthyoplankton index, and calibrated it to the absolute biomass estimates produced by the Daily Egg Production Method in the early 1980s. Anchovy spawning biomass was very low, near 10,000-20,000 tons, in the early 1950s when CalCOFI sampling began. Abundance then increased and fluctuated between 0.5 and 2 million tons from 1960 through 1990. After 1990, spawning biomass fluctuated around 200,000 tons, briefly increased dramatically in 2005-2006, then declined drastically over four years to below 20,000 tons in 2009-2011. CalCOFI Bongo net samples collected after 2011 are not yet available for analysis, but the continuous underway egg sampling conducted during CalCOFI cruises indicated continued low abundance through 2015.

 Photo copyright by  Ron LeValley .

Photo copyright by Ron LeValley.

This remarkable decline in anchovy abundance occurred in the absence of a significant fishery. Present annual catches of a few thousand tons are small by historical comparison, but the exploitation rate may now be relatively high given the low stock abundance. The decline in anchovy abundance also coincides with recent reports of die-offs and reproductive failures of top predators that rely on anchovy for food. 

This research was described in a recent article in the journal Fisheries Research.

Pacific herring (Clupea pallasii) occur throughout the North Pacific ocean and are vitally important in both pelagic and coastal food webs. Herring are important prey for larger fish, seabirds, and marine mammals. They lay their eggs on coastal seagrasses and algae, and those eggs feed predator species that forage along the shore (e.g., invertebrates, birds, and mammals such as raccoons and black bears). Herring were integral to ancient human cultures, and are still important to native and other modern fisheries. With cooperation from California Audubon scientists, we are studying trends and variability in herring populations along the west coast of the U.S. and Canada. We are finding that herring abundance in these areas has been declining for the past few decades, which may negatively impact numerous other species, as well as fisheries yield. Our study aims to describe the temporal variability of this decline as well as how it is varies between different areas along the west coast. 

Information about sandlance and capelin projects is coming soon.

Farallon Institute scientists have been analyzing diet data from three puffin species in Alaska. Puffin diet data were collected since the 1970s by the USGS Alaska Science Center, Alaska Maritime National Wildlife Refuge Seabird Monitoring Program, and the Institute for Seabird Research and Conservation. Researchers from these agencies collected data from approximately 40 sites around the Gulf of Alaska and across the Aleutian Islands.  

 Tufted puffin. Photo copyright by  Ron LeValley .

Tufted puffin. Photo copyright by Ron LeValley.

In order to study puffin diet, field biologists collect samples of the fish and invertebrates (such as squid) that adult puffins bring back to nest burrows to feed to chicks. These diet samples are brought to the lab where they are identified to species, weighed, and measured. For diet analysis, Farallon Institute organized the sample data in a database that contains over 100,000 records of the fish and invertebrate samples collected at the nest burrows, and their sizes. Research and data collection are ongoing, but we have three major analyses of these data.

Temporal variability -- We recently published a paper describing temporal variation in puffin diet from 1978-2012. Variation in puffin diet over time can be indicative of changes in the local fish community, which may be driven by large-scale environmental factors.

Geographic variability -- By studying puffin diet at so many sites, we can also explore how fish communities might be different from place to place.  In the Gulf of Alaska and Aleutian Islands, the ocean habitat around puffin colonies varies.  Colonies in the east are more continental shelf-oriented than the sites in the west, which are in a more oceanic system (see map below, and the proximity of colonies to the 2000-m isobath).  As such, puffin diet varies in accordance with the habitat characteristics of these sites.  A manuscript on this geographical variation is in progress.

Fish condition -- Condition of fish can be determined from their size and weight.  We are currently analyzing these size measurements to create a condition index that can be related to environmental conditions in the ecosystem.

 Locations of monitored puffin colonies in Alaska, shown with a 50-km foraging radius (blue circles).  The black line is the 2000-m isobath.

Locations of monitored puffin colonies in Alaska, shown with a 50-km foraging radius (blue circles).  The black line is the 2000-m isobath.

Farallon Institute has been working in partnership with Pew Charitable Trusts to facilitate workshops for scientists on the topic of "Best practices and guidelines to document effects of fisheries competition on seabirds, with an emphasis on penguins". Workshops were held in October 2015 in Cape Town, South Africa, and January 2016 in Seattle, Washington. More information can be found here.

 Common murre with lunch. Photo copyright by  Ron LeValley .

Common murre with lunch. Photo copyright by Ron LeValley.